Laser dies are commonly used in optical communication systems to transmit optical signals through optical fibers. Each laser die is typically packaged as an optical transmitter module, which can be mounted on a printed circuit board (PCB) and coupled to an optical fiber of an optical transceiver. Thus, an optical transmitter module must be designed to be electrically and physically attached to a PCB, and to be connected to an optical transceiver.
A conventional optical transmitter module comprises a header with a metal post on which an edge-emitting laser die is mounted. The header includes lead pins, which are mutually electrically isolated. Two of the lead pins are electrically connected to the laser die to provide driving currents to the laser die. The lead pins are used to couple the optical transmitter module to a PCB so that the optical transmitter module can be electrically and physically attached to the PCB. The optical transmitter module also comprises a metal housing assembly that is coupled to the header. The metal housing assembly includes a fiber ferrule with an opening to receive an optical fiber. The metal housing assembly is designed to secure a lens in the form of a ball lens or a glass a-sphere at a position between the header and the fiber ferrule opening so that optical signals from the laser die are efficiently focused onto the optical fiber inserted into the fiber ferrule opening.
A concern with the conventional optical transmitter module is that the edge-emitting laser die is mounted at ninety degrees on the metal post of the header, which complicates the wire bonding of the laser die. Furthermore, the metal post must function as a heat sink since the configuration of the optical transmitter module with respect to the lens requires the use of high driving currents for the laser die.
Another concern with the conventional optical transmitter module is that the ball lens or glass a-sphere is costly and needs special mounting provisions in order to ascertain the fiber receives the transmitted light in an efficient way.
Still another concern with the conventional optical transmitter module is that the header lead pins need to be bent in complex ways to attach the module to a PCB and to connect to an optical transceiver, which can compromise signal and structural integrity.
In view of these concerns, there is a need for an optical transmitter module that does not require a header with a metal post, a lens in the form of a ball lens or a glass a-sphere and header lead pins that must be bent in complex ways to attach the module to a PCB and to connect the module to an optical transceiver.